To lift a vessel front the water without injury to itself, and to place it upon a cradle or carriage for transportation without injury to the carriage, it is necessary to make careful provision to insure the equal distribution of the unequal weight of the vessel, so as to bring no more load upon one part of the carriage than upon another. This result Captain Eads proposed to secure by the use of a system of hydraulic presses built into the pon toon. There will be a number of these presses arranged in longitudinal order and all connected with one another by water-pipes, and by their in troduction, it is affirmed, the weight of the vessel, when raised from the water, will be equally distributed over the entire surface of the cradle. The deck of the pontoon will be furnished with six rails for the carriage which will transport the vessel 51,fig. 6). The carriage will be mounted upon trucks. It will be provided, also, with a keel-block the entire length of the vessel, hinged in such a manner as to be adjustable to the shape of the vessel's keel. The supports under the keel-block and the other sup ports of the vessel will rest on large steel rods in which a thread will be cut for an adjusting nut, and the upper ends of these rods under the ves sel's bottom will carry on a universal joint a bearing-block having an area of 12 square feet. These bearings will be adjusted in position against the vessel's bottom. They will be cushioned with rubber, to form a firm yet elastic support.
The operation of lifting a vessel will be about as follows: The carriage will be run from the railway upon the. pontoon and locked in position (fig. 4). The water will then be let into the pontoon by the sluice-gates, and it will go down with the carriage resting upon it until it has reached a suffi cient depth to allow the vessel to be floated in over it. The vessel will then be brought in over the pontoon with the centre of gravity' over the centre of the pontoon, and adjustable guides from the sides of the dock worked by hydraulic power will bring the vessel into position centrally over the car riage. The pontoon pumps will now be set to work, and the pontoon, with the carriage upon it, will rise up under the vessel, and just previous to actual contact with it the pressure pumps will be set to work and the entire system of rams will be forced up against the keel, bottom, bilges, and sides of the vessel. The pontoon pumps will continue to lift the pon
toon out of the water with the vessel upon it until the latter has reached the proper height; the a.djusting nuts before described will be run down on the thread of the supports until they have a firm bearing on the cross guides of the carriage. When this has been done, the valves of the rams will be opened, the rains will recede downward into the pontoon, and the weight of the vessel will then have been transferred from the rams to the carriage (fig. 5).
The vessel will now be ready to be transported on the railway. This will be specially constructed with substantial foundations of road-bed, and will be furnished with six tracks of ordinary gauge. The rails, which will be of steel, will be extra heavy (one hundred and twenty pounds to the yard), and will rest on steel cross-ties extending across all six tracks. The width of the roadway will be about 5o feet. The wheels of the carriage trucks will be double-flanged, to lessen the liability to derailment. The motive-power will be obtained from locomotives of exceptionally great tractive power which will impose a weight of at least one hundred tons on the driving-wheels. These locomotives will be attached directly to the load, three in front (jig-. 7), and three behind, as pushers, if necessary. As any pronounced deflection from a straight line will be attended with risk, an ingenious device in the form of a floating turn-table has been proposed, to permit of the turning out of a vessel to allow another to pass or to per mit of a change of direction. To float the vessel free from the carriage in the waters of the opposite ocean, when it reaches the dock at the other ter minus of the line the same series of operations will be gone through with, but in reverse order.
It should be stated, in conclusion of the description of this ingenions scheme, that some doubts have been expressed among naval engineers as to the ability of vessels to withstand uninjured the strain of such treatment as they would be subjected to in this systein of land transport.